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Results
Abstract Low permeability and complexities of rock formation in tight gas resources make it more complicated to predict well production performance and estimate gas recovery. To produce from the unconventional resources in the case that formation rock is not sensitive to damage caused by liquid invasion, hydraulic fracturing is the most common stimulation treatment to improve the production to the excepted economically rate. In term of reservoir geometry, tight sand formations are normally stacks of isolated lenses of sand bodies that are separated by shale layers. Each sand lens varies in shape and size and acts as a trap for original hydrocarbon accumulations. The sand lenses parameters such as length and width can play important role in controlling gas recovery from hydraulically fractured tight gas reservoirs. This study shows the effect of drainage pattern of the lenticular sand bodies on production performance and ultimate gas recovery in tight gas formations. Analytical and numerical simulation approaches are used in order to understand the effect of hydraulic fracture parameters and also attribution of sand lens size and shape to the drainage pattern and gas recovery in hydraulically fractured tight sand gas reservoirs. The results highlighted that in tight gas with massive hydraulic fractures, sand lens size in the direction perpendicular to hydraulic fracture wings has the major impact on gas recovery. Sand lens size in the direction parallel to hydraulic fracture wings does not have significant effect on gas recovery. When the sand lenses are isolated and small in size, from a singlewell-enhancement perspective, the gas recovery will increase significantly by performing massive hydraulic fracturing through isolated lenses.
- Asia > Middle East (0.48)
- North America > United States (0.29)
- Europe > Norway > Norwegian Sea (0.25)
- Research Report > New Finding (0.69)
- Research Report > Experimental Study (0.55)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.70)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.55)
Abstract Economic production from an unconventional gas reservoir is possible only if a complex fracture network can be created that connects a huge reservoir area to the wellbore effectively. This fracture network can be created by hydraulic fracturing. Several techniques can be used to present hydraulic fractures in a simulation model. In a simple model it is assumed that the fractures lie in the single plane of local tartan grid cells that best approximates the true geometric orientation of the fracture. The local refinement is symmetrically placed within the plane of host cells and has small cells close to the fracture that logarithmically increase in size away from the fracture. Explicitly calculated transmissibility multipliers on the faces of the cells that intersect the fracture are used to model the flow between matrix and the hydraulic fracture. The spacing and conductivity of the hydraulic fractures are critical parameters that control well performance. A new reservoir modeling and simulation technique has been developed for these complex fracture networks that combines discrete fracture network (DFN) modeling and unstructured fracture (UF) modelingto simulate well performance and improve stimulation design. This is very important for modeling and simulation of a well with hydraulic fractures in a shale gas reservoir with natural fractures. Results from this new model show a gas shale reservoir can be drained more effectively if a complex fracture network can be created by hydraulic fracture stimulation. In addition to a large increase in the production, the number of fracture treatment stages can be reduced if a high-conductivity fracture can be created, adding to the economic viability of the development of unconventional gas sources. The modeling and simulation technique presented in this paper can help identify stimulation and completion strategies that will significantly improve well performance and ultimate recovery from an unconventional gas reservoir.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.54)